The Trump administration’s drug pricing plan leaves unclear whether access to cutting-edge, targeted therapies known as precision medicine will flourish or flounder, an executive for the brand-name drug industry trade group said.

“There’s a lot of question marks—literally in the blueprint itself and the RFI [request for information] that followed as well,” Randy Burkholder, vice president of policy and research for Pharmaceutical Research and Manufacturers of America, said at a May 24 luncheon about the White House plan released May...